  {  Petrova Tatjana
     2012 / 09 / 25
     This program can find out if the point belongs
     to the polygon.}


program PointAndPolygon;

{$APPTYPE CONSOLE}


uses
  SysUtils;

var
  a, S , i , e , f , S1 : integer;
  fin : textfile;
  mass,mass1 : array of integer;

begin
  assignFile(fin, 'input.txt');
  reset(fin);
  readln(fin,a);
  Setlength(mass,a);
  Setlength(mass1,a);
  for i:= 0 to a-1 do
  begin
    readln(fin,mass[i],mass1[i]);
  end;
  for i:=1 to (a-2) do
  begin
    S:=S+abs(mass[0]*mass1[i]-mass[i]*mass1[0]+mass[i]*mass1[i+1]-mass[i+1]*mass1[i]+mass[i+1]*mass1[0]-mass[0]*mass1[i+1]) ;
  end;
  readln(fin,e,f);
  closeFile(fin);
  for i:=0 to (a-2) do
    S1:=S1+abs(+e*mass1[i]-mass[i]*f+mass[i]*mass1[i+1]-mass[i+1]*mass1[i]+mass[i+1]*f-e*mass1[i+1]) ;
  S1:=S1+abs(e*mass1[0]-mass[0]*f+mass[0]*mass1[a-1]+mass[a-1]*mass1[0]+mass[a-1]*f-e*mass1[a-1]) ;
  if (S=S1) then
  begin
    writeln('Yes!')
  end else 
  begin
    writeln('No!');
  end;
  readln;



end.

















